High-performance VOC co-polymer rubber elastomeric sealant that seals leaks fast - even in standing water. Seals leaks that asphalt can't. Roofs move - wind gusts and changes in weather put roofs in constant dynamic motion. Most roof caulks dry hard and crack. They can't handle the movement like Through the Roof! It's the waterproof, ultra-elastic sealant made to permanently stop and prevent roof and gutter leaks.